civils mains 2013 CHEMISTRY Paper-II

Time Allowed: Three Hours

Maximum Marks: 250

QUESTION PAPER SPECIFIC INSTRUCTIONS

Please read each of the following instrnctions carefully before attempting questions.
There are EIGHT questions divided in Two Sections and printed both in HINDI and in ENGLISH.
Candidate has to attempt FIVE questions in all.
Question no. 1 and 5 are compulsory and out of the remaining, THREE are to be attempted choosing
at least ONE from each section.
The number of marks carried by a question/part is indicated against it.
Answers must be written in the medium authorized in the Admission certificate which must be stated clearly on the cover of this Question-cum-Answer booklet in the space provided. No marks will be given for answers written in medium other than the authorized one. Coordinate diagrams, wherever required, shall be drawn in the space provided for answering the question iteself.
Unless otherwise indicated, symbols and notations have their usual standard meanings.
Assume suitable data, if considered necessary, and indicate the same clearly.
Attempts of questions shall be counted in chronological order. Un less struck off, attempt of a question shall be counted even if attempted partly. Any page or portion of the page left blank in the answer book must be clearly struck off.

SECTION-A

Q. Addition of bromine to ethylene in methanol gives bromomethyl methyl ether as one of the products. Formulate the reaction and give mechanistic explanation for the formation of this product. 10
The dehydrobromination of isopropylbromide requires several hours of refluxing in alc. KOH, whereas, in dehydrobromination can be carried out in less than a minute at room temperature. Give reason for this observation. 10
Explain why the rate of the reaction:
<img src='./qimages/92-1c.jpg'>
gradually decreases with the progress of reaction. 5
Describe a simple chemical test to distinguish between aniline and benzylamine. 5
Isobutene is treated with conc. HBr in the presence of dibenzoyl peroxide in acetonitrile solution. Formulate the reaction and give explanation for the formation of the product. 10
Write the products and in the following reactions
<img src='./qimages/92-1e.jpg'>

Q. 2. Explain why ion peak is observed in mass spectrometry. Indicate, which electron is most likely to be lost in the ionization of following compounds and write the radical cation formed:
CH2 0
CH2 CH2
C6HsCH2CH3
CH3CJ.

l-chloromethyl cyclopropane on hydrolysis chiefly gives three products. Write a mechanism to show their formation. 15

An organic compound reacts with aq. HOG.

<img src='./qimages/92-2c.jpg'>

Write the following
If is dextro, comment on the optical activity of the product.
If concentration of OH- is doubled, how rate of the reaction will change
Draw energy profile diagram for the reaction.
Write the mechanism of the reaction.
If C2Hs and C6Hs in are replaced by comment on the optical activity of the product. 15

Q. 3. The compound C2H2BrCI exhibits three isomeric structures. The three isomers in proton NMR exhibit two doublets each having J 1.5, 9 and 14 Hz respectively. Write the structures of isomers and assign J values to each one of them. 20
Describe using appropriate reagents and conditions a method to achieve the following transformations
<img src='./qimages/92-3b.jpg'>

(c)Write the products of the following reactions and give the suitable mechanism
<img src='./qimages/92-3c1,2.jpg'>

Q. 4. Identify and in the following reactions. Explain their formation.
<img src='./qimages/92-4a1.jpg'>
<img src='./qimages/92-4a2.jpg'>
How will you prepare styrene .using Wittig reaction? Write the name of reactants and explain the mechanism of the reaction. 20
Write a mechanism for the following conversion
<img src='./qimages/92-4c.jpg'>

SECTION-B

Q. 5. Describe the products obtained by the treatment of cis- and trans-2-phenyl-I-cyclohexanol with H3P04 .
What is the major product of each of the following reactions?
<img src='./qimages/92-5b.jpg'>
Give the mechanisms of the reactions.

(c)Identify and in the following

<img src='./qimages/92-5c.jpg'>


How many NMR signals do you expect in
<img src='./qimages/92-5d.jpg'>
Explain their nature.

Formulate the reaction:
<img src='./qimages/92-5e.jpg'>
and give a mechanism to explain the formation of the product. 10x5

Q. 6. An organic compound C4HsO gives a strong absorption band at 1710 cm-I in IR spectrum. In proton NMR, it gives signa(at 8 1.1 (triplet), 2.1 (singlet) and 2.3 (quartet). Write the, likely structure of the compound and assign the 8 values. 20
Write the steps involved in the conversion of 4-bromobutanal to 4-methoxybutanal. 15
Amino acids on treatment with ninhydrin give intense blue colour. What is this colouration due to I5
Q. 7. write the name and structure of one polymer having
Linear structure
Network structure
Three dimensional structure.
Write the mechanism for the polymerization of phenol and formaldehyde in the presence of

Explain why free radical polymerization 3-butadiene leads to macromolecules having two different types of monomer units. 15
Write the name and structure of two purine and pyrimidine units present in DNA. Also explain why most of the genetic materials contain DNA and not RNA. 15

Write the products of the following name reactions
<img src='./qimages/92-8a.jpg'>
<img src='./qimages/92-8a1.jpg'>

Identify and in the following
<img src='./qimages/92-8b.jpg'>